Hesperocyparis guadalupensis, commonly known as Guadalupe cypress, is a species of western cypress from Guadalupe Island in the Pacific Ocean off the western coast of Mexico's Baja Peninsula. It was previously known as Cupressus guadalupensis until 2009. It is a medium-sized tree with fine green to blue-green foliage. In its native habitat it depends on water from the fogs that envelop high ground in the northern half of the island. It became an endangered species due to feral goats living on Guadalupe Island that – for more than a century – prevented new trees from growing. In 2005 the goats were finally removed from the tree's island home as part of an island restoration project. New trees are growing and other plants are beginning to recover, though the future of the species is not yet assured. Guadalupe cypress is closely related to the vulnerable Tecate cypress, which grows on the mainland in Baja California and southern California. It is used as an ornamental tree in Mediterranean climates, particularly in Europe, but has no other significant human uses.
Description Guadalupe cypress is a coniferous evergreen tree with a dome-shaped and broad crown when fully mature. The species is variable in size, with mature trees reaching 12–20 metres (39–66 ft) tall, though they are noted as being towards the lower end of this range in their native habitat in the 2000s. The first scientific description recorded them as growing to "40 feet high or more". The bark of the tree is fairly smooth, but thin layers will peel off the trunk. The color of the bark may range from cherry-red to dull gray brown. The bark of the larger branches is of similar texture and color as the trunk. In the first year a new shoot will be yellow-green to brown. The foliage grows in dense sprays, dark blue-green or glaucous blue in color. The leaves are scale-like, 1.5–2 millimeters long, in four rows on rounded (not flattened) shoots. The texture of the foliage is soft; when crushed, it has a light resinous aroma. The leaf scales are not shed from the branchlets, but instead the entire small twig is shed after two to three years. The branchlets on the ends of branches may reach a length of 2–3 centimeters, but will only be 1 millimeter thick. The seed cones are nearly spherical, with eight to ten horn-shaped scales, narrow at the base and wide at the top, with a pointed tip. They measure 3–3.5 centimeters in diameter. They are green during growth and ripen to be gray-brown or brown. Inside the cone are approximately 70 to 100 seeds, brown with a light waxy coating described by botanists as glaucous. The seeds are much larger than those of other western cypress trees, weighing two to seven times as much. Closed, but already ripe, cones still on the trees will also open after being exposed to the heat of a fire. Unlike the cones of the related Tecate cypress (Hesperocyparis forbesii), the cones will also open after drying for several months on the tree without needing to be exposed to fire. Each seed is about 5–6 millimeters long with a small wing structure about 1 millimeter. The cones and seeds are fully ripe 15 to 18 months after fertilization. The pollen-producing cones (strobili) have 14 to 18 scales. This is another characteristic that botanists use to distinguish it from the Tecate cypress, which only has 10 to 14 scales on its pollen cones. The strobili are also rather large, about 6 millimeters long and 2–5 millimeters in diameter. The pollen is produced from October to November when growing in California, while in France and Italy they have been observed producing pollen from December to March. The lifespan of cypress trees can be estimated from the number of annual growth rings found in the trunks of dead trees. Using this measurement, the average longevity is estimated at 150 to 160 years for a tree with a 50 centimeter diameter, though one trunk examined by botanical explorer Edward Palmer with a diameter of approximately 64 centimeters had 236 growth rings. The seedlings are very similar to all other western cypress species, with three to five long, thin, needle-like seed leaves that start out upright and then spread outwards from the stem. Each leaf is usually between 8 and 12 millimeters long. The juvenile leaves also resemble the needle-like seed leaves, but are not quite as long or as thick or fleshy in texture. In the second to fourth year of life the young tree will start to produce adult foliage rather than another set of juvenile leaves. In the first year of growth, given favorable growing conditions, young trees will reach an average of 40 to 45 centimeters in height. By the end of a second year they will reach 110 centimeters. This rapid growth can continue, with a new tree reaching an estimated 9.7 meters in its first decade.
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